1. Field of the Invention
In the automobile industry, every year, more and more electronic devices find their way into vehicles. If the trend continues, by the end of the 1990s, the electronic content of vehicles will at least double.
The Society of Automotive Engineers (SAE) encourages the entire automotive industry to develop a standard data link, preferably a medium-speed (Class B) multiplexed data communications system. The SAE established Recommended Practice J1850 (a set of technical requirements and parameters) has already been accepted by the industry as the communications link.
2. Description of the Prior Art
When using software to generate puse codes that meet J1850 requirements and then to transmit code from a microcontroller (MCU) over a communications bus (bus) to a second MCU and then back over the bus to the first MCU, the transfers occurred too slow. A first try involved an inexpensive MCU which operated at about one-fourth the speed required.
To resolve the speed problem and cost, a combination of an MCU and a cooperating hardware circuit appeared to provide a likely combination for achieving the speed and cost sort for the task. Effort extended to seek such a combination resulted in the computer driven symbol encoder decoder (SED) of the present invention.